The present invention relates to a saw blade clamping mechanism for a power tool, and especially relates to an improved blade clamping mechanism for a cutting tool.
A cutting tool, such as a reciprocating saw for example, typically comprises an elongate blade mounted on a top end of a driving pole for performing cutting. Therefore, it is important to design a saw blade clamping mechanism which allows quick replacement of the saw blade.
U.S. Pat. Nos. 6,209,208 and 6,725,548 disclose a saw blade clamping mechanism which mainly comprises a driving spindle on which a longitudinal slot and a radial spindle orifice are formed, a sleeve which is immovable relative to the spindle, a pin held in a receiving orifice of the sleeve, and a cam member surrounding the sleeve. The cam member could be positioned between a first circumferential position and a second circumferential position and has an inner curved surface having varying radiuses. When the cam member is positioned at the first position, the curved surface resists the outside end of the pin and the inside end thereof gets through the radial spindle orifice, then inserts into the longitudinal slot; when the cam member is positioned at the second position, the curved surface disengages from the outside end of the pin and the inside end retracts back from the longitudinal slot of the spindle. Therefore, to mount a saw blade to the power tool, the operator should insert the blade into the longitudinal slot of the spindle and turn the cam member to the first position. Under constraining of the cured surface, the pin will be pushed to the spindle along the sleeve orifice and gets through the spindle orifice and finally inserts a hole of the blade, thus the blade is clamped tightly on the spindle. To dismount the blade, the operator should turn the cam member to the second position to make the cam member disengage from the pin, then the inside end of the pin will retract from the hole of the blade and the blade could be taken away.
Mounting or dismounting of the blade through the saw blade clamping mechanism described hereinabove is not too complex, just by operation of the cam member, but the operator must keep the cam member at the second position before inserting the blade and make sure the cam member is at the first position after the blade is mounted, such that normally the operator should hold the blade with one hand and at the same time grasp the cam member by the other hand, which makes the operator feel uncomfortable.